When a soil treatment area has been organically and/or hydraulically overloaded it is possible to remediate the STA using an advanced pretreatment unit. When we use a conventional system we are relying on the soil to remove the many remaining solids and organic materials along with bacteria and viruses.If a unit is installed that will meet secondary treatment levels or better, the effluent will contain few solids and little remaining organic material as measured by the BOD5 test. This additional step reduces the amount of total suspended solids (suspended solids value of less than 30 mg/L, compared to typical septic tank effluent
